A part of a plant gene is identical to a yeast gene!!!

"Alexander Kraev" bckraev at aeolus.ethz.ch bckraev at wawona
Sat Apr 29 06:00:29 EST 1995

In article <3nrqeg$3qi at knot.queensu.ca>, 3mam25 at qlink.queensu.ca (Malboobi M Ali) writes:
>We have isolated an inducible plant cDNA and sequenced it partially so far.
>We found that this cDNA has 99% homology to a yeast negative regulator 
>gene only from N-terminal and no homology to that gene from C-terminal.
>To be percise, only 4 nucleotide differed out of 416 nucleotide at the 
>N-terminal side of the cDNA (sequencing error!!). 
>How such level of homology is possible in a stretch of 416 bp or more 
>(We continue sequencing it further)?
>It should not be a contamination because C-terminal sequence does not 
>show any homology...

The fact that Clontech catalog in the pre-made library section states that
their libraries are no longer made using yeast RNA as carrier ( during cDNA
preparation ) means that such things as yours must have happened in the past.
Although I think that your cDNA is a chimera, it is difficult to
figure out, at what step of library preparation it was generated. The likely
possibilities are: fungal contamination of the original material, use of
yeast RNA as carrier anytime during cDNA preparation, and overgrowth of the
library during primary plating, so that two unrelated clones have recombined. 
Perhaps you should try your C-terminal part as probe on other cDNA libraries. 
Hope this helps,

Alexander Kraev, Ph.D.                 Internet: bckraev at aeolus.ethz.ch
Lab. of Biochemistry III               Phone: 0041-1-632-31-47
Swiss Federal Institute of Technology  FAX:   0041-1-632-12-13
CH-8092 Zurich
"Some ideas are obscure not because they are complex, but because they 
 are excluded from our circle of comprehension" - Kozma Prutkov

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